Ok it hops around a bit.
With icons, the distance is in yards, but it's a bit different. Probably easiest to start with in close. If an icon says:
0 it means the vehicle is between 0 and 100 yards.
200 it means it's between 101 and 300 yards.
400 it means it's between 301 and 500 yards.
600 it means it's between 501 and 600 yards.
800 it means it's between 601 and 900 yards.
When it shows 1k, I think the way it works is if it says 1k, it's within 1000-1100 yards. If it switches to 1.0k, it's within 900-1000 yards(?).
And anyone that wants to quibble that it switches between 0 and x99, then swaps over to the next one up at 100 and so forth, I salute your gunnery that is precise enough for one yard to make a difference.
When people are on channel talking about a bandit coming in at 15k or similar, generally speaking they mean 15,000 feet altitude.
Wiley.